Since I ran into someone doing it correctly, I thought I’d remind you about the dieresis, those two dots that look like an umlaut above a letter in English.
Only a few words retain the dieresis now, but naïve is one of them. It means you pronounce the two vowels separately, not together. “Naïve” is really a two-syllable word!
To get those dots over a letter i, hold down the Alt key while you type 139 on the numeric keypad.